{ "dataType": "CVE_RECORD", "cveMetadata": { "cveId": "CVE-2024-26689", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-02-19T14:20:24.154Z", "datePublished": "2024-04-03T14:54:50.885Z", "dateUpdated": "2026-08-05T11:26:42.116Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:26:42.116Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nceph: prevent use-after-free in encode_cap_msg()\n\nIn fs/ceph/caps.c, in encode_cap_msg(), \"use after free\" error was\ncaught by KASAN at this line - 'ceph_buffer_get(arg->xattr_buf);'. This\nimplies before the refcount could be increment here, it was freed.\n\nIn same file, in \"handle_cap_grant()\" refcount is decremented by this\nline - 'ceph_buffer_put(ci->i_xattrs.blob);'. It appears that a race\noccurred and resource was freed by the latter line before the former\nline could increment it.\n\nencode_cap_msg() is called by __send_cap() and __send_cap() is called by\nceph_check_caps() after calling __prep_cap(). __prep_cap() is where\narg->xattr_buf is assigned to ci->i_xattrs.blob. This is the spot where\nthe refcount must be increased to prevent \"use after free\" error." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - The freeing half of the race executes in `handle_cap_grant()`/`ceph_fill_inode()` while parsing `CEPH_MSG_CLIENT_CAPS` messages and reply traces received from the remote Ceph MDS, so a co-tenant CephFS client, a malicious/compromised MDS, or a MITM on the (by-default unencrypted) msgr connection controls the timing and content of the free. The freed buffer's contents are additionally marshalled into `msg->middle` and transmitted back over the network to the MDS.\nAC:L - The attacker drives both sides of the race — local/co-tenant `setxattr` traffic opens the unlocked `__prep_cap()`→`__send_cap()` window, while concurrent access to the same inode from another client forces the MDS to emit the cap grant with a higher `xattr_version` that drops the last reference — and the sequence can be retried without limit until the window is hit.\nPR:L - Exploitation requires only an ordinary unprivileged account with write access to a file on an already-mounted CephFS (no capabilities are checked anywhere on the `setxattr`→`ceph_check_caps`→`__prep_cap` path), or an equally unprivileged co-tenant account on the same shared CephFS.\nUI:N - No victim action is needed at exploit time; the CephFS mount is pre-existing deployment configuration, and the attacker's own syscalls and MDS traffic supply every step of the race.\nS:U - The corruption is confined to kernel heap objects within the same kernel security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - This is a use-after-free whose stale `vec.iov_base`/`vec.iov_len` are read back and sent to the MDS as the cap message middle section, leaking reallocated kernel heap contents to a remote peer, and heap grooming of the small `kmalloc-64` `ceph_buffer` object generalizes this into an arbitrary kernel-memory read.\nI:H - `ceph_buffer_get()` performs a `kref_get()` increment directly into freed memory, corrupting a refcount field of whatever object is reallocated into that slab slot, and the later `ceph_buffer_put()`/`kvfree()` on stale pointers yields a double-free/arbitrary-free — both standard stepping stones to arbitrary write and control-flow hijack.\nA:H - The use-after-free was caught by KASAN and, unmitigated, corrupts slab metadata and refcounts leading to oops, double-free and kernel panic, which the attacker can trigger repeatedly." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ceph/caps.c" ], "versions": [ { "version": "9030aaf9bf0a1eee47a154c316c789e959638b0f", "lessThan": "8180d0c27b93a6eb60da1b08ea079e3926328214", "status": "affected", "versionType": "git" }, { "version": "9030aaf9bf0a1eee47a154c316c789e959638b0f", "lessThan": "70e329b440762390258a6fe8c0de93c9fdd56c77", "status": "affected", "versionType": "git" }, { "version": "9030aaf9bf0a1eee47a154c316c789e959638b0f", "lessThan": "f3f98d7d84b31828004545e29fd7262b9f444139", "status": "affected", "versionType": "git" }, { "version": "9030aaf9bf0a1eee47a154c316c789e959638b0f", "lessThan": "ae20db45e482303a20e56f2db667a9d9c54ac7e7", "status": "affected", "versionType": "git" }, { "version": "9030aaf9bf0a1eee47a154c316c789e959638b0f", "lessThan": "7958c1bf5b03c6f1f58e724dbdec93f8f60b96fc", "status": "affected", "versionType": "git" }, { "version": "9030aaf9bf0a1eee47a154c316c789e959638b0f", "lessThan": "cda4672da1c26835dcbd7aec2bfed954eda9b5ef", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ceph/caps.c" ], "versions": [ { "version": "2.6.34", "status": "affected" }, { "version": "0", "lessThan": "2.6.34", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.210", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.149", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.79", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.18", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.7.6", "lessThanOrEqual": "6.7.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.8", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "5.10.210" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "5.15.149" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "6.1.79" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "6.6.18" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "6.7.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "6.8" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/8180d0c27b93a6eb60da1b08ea079e3926328214" }, { "url": "https://git.kernel.org/stable/c/70e329b440762390258a6fe8c0de93c9fdd56c77" }, { "url": "https://git.kernel.org/stable/c/f3f98d7d84b31828004545e29fd7262b9f444139" }, { "url": "https://git.kernel.org/stable/c/ae20db45e482303a20e56f2db667a9d9c54ac7e7" }, { "url": "https://git.kernel.org/stable/c/7958c1bf5b03c6f1f58e724dbdec93f8f60b96fc" }, { "url": "https://git.kernel.org/stable/c/cda4672da1c26835dcbd7aec2bfed954eda9b5ef" } ], "title": "ceph: prevent use-after-free in encode_cap_msg()", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-02T00:14:12.664Z" }, "title": "CVE Program Container", 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